Ventilating device for a multicylinder drier

ABSTRACT

A device is used for ventilating a pocket of a multicylinder drier. The pocket consists of a felt guided by a felt roll. A partition extends transversely to the felt and is located opposite the felt roll belonging to the pocket. The invention is particularly characterized in that the marginal part of the partition pointing toward the felt roll consists of sections each of which has its own adjusting device so that a gap of desired width for the flow of air may be produced between the surface of the felt roll and the edge of the section.

United States Patent Berg et al.

[54] VENTILATINGDEVICE FOR A MULTICYLINDER DRIER [72] Inventors:Nils-Christian Berg, Turuku; Mluri Altos Solninen, Naantali, both ofFinland Valmet 0y, Helsinki, Finland Sept. 1, 1970 [73] Assignee:

[22] Filed:

[56] References Cited UNITED STATES PATENTS 3,110,575 11/1963 Justus..34/ll1 [451 June 13,1972

3,376,653 4/1968 Daane ..34/1 11 Primary E.mminerCarroll B. Dority, Jr.Attorney-Richards and Geier [57] ABSTRACT A device is used forventilating a pocket of a multicylinder drier. The pocket consists of afelt guided by a felt roll. A partition extends transversely to the feltand is located opposite the felt roll belonging to the pocket. Theinvention is particularly characterized in that the marginal part of thepartition pointing toward the felt roll consists of sections each ofwhich has its own adjusting device so that a gap of desired width forthe flow of air may be produced betvveen the surface of the felt rolland the edge of the section.

6 Claims, 8 Drawing figures edge of the partition extending close to thesurface of the felt roll and said partition dividing the space betweenthe drying cylinders into two parts from one of which an air currentinduced by the running of the machine flows in the direction into thepocket and into the other of which air flows from the direction of thepocket. I i

It is known in previous art that ventilation is poor in the pockets of amulticylinder drier, which pockets are found under the upper cylindersand above the lower cylinders, and which fact results in lowered dryingefficiency of the machine and in non-uniform moisture profile of the webwhichis being dried because as a rule the humidity of the air in the.pockets is higher in the center of the pocket than at its ends. Thedrying felt has previously been impermeable to air. Nowadays the use ofa drying felt permeable to air, a so-called drying wire, has beenincreasingly adopted. It is to be noted that then currents passingthrough the drying felt are produced by the rotating parts of themachine and by the moving drying felt, which are directed on one handfrom the spaces surrounding the pockets into the pockets and on theother hand from the pockets into the spaces surrounding them. As aconsequence, the ventilation of the pocket is considerably improved,whereby the drying efficiency of the machine and the uniformity ofdrying are increased. It is obvious that the air flows passing throughthe felt are greater accordingly as the speed of operation of themachine is higher. It is furthermore known in previous artto place inthe space outside the pockets additional devices which are used by meansof various blowing actions to boost the flow through the felt or bymeans of which the state of the air passing through the felt is socontrolled that the uniformity of moisture content of theweb in thecrossmachine direction improves. It has been observed that infast-running driers the flow from the spaces surrounding the pocketsthrough the wire into the pockets as a rule is a multiple of the dryingair flow which is available for additional devices improving theventilation. For this reason in fast machines the possibilities ofinfluencing both the state and quantity of the air flowing into thepockets decrease with increasing operating speed. Quite often, inaddition, the airflow into the pockets has such high magnitudethat itsincrease is in fact detrimental.

The observation may also be made that all the air flowing into thepocket is not fresh air arriving from. the surroundings but that part ofit is air which circulates around the roll,

described above. The invention is characterized in that opposite to thefelt roll, outside the pocket, between two drying cylinders has beenplaced a partition with its marginal part pointingtowards the'felt rollconsisting of sections placed in continuation of each otherin thecross-machine direction, each section individually being provided withregulating devices for .such adjustment that it is possible to producebetween the surface of the felt roll and the section (the edge) a gap ofdesired magnitude, through which the air can flow in the direction ofrotation of the felt roll from one side of the partition to the other.The sections of the edge portion of the partition pointing towards thefelt roll maybe turnably attached to the partition. Also, the partitionin its entirety or at least its marginal part closest to the felt rollmay consist of sections transversal to' the felt which have beenarranged to be movable radially with-reference to the surface of thefelt roll,

. like shutters. It is advantageous to place on the side of thepartition from which flow into thepocket takes place, afresh-airintroducing nozzle with closing device corresponding to eachsection in the marginal portion of the partition, the closing device ofwhich has been arranged to operate so that when the free edge of thesection of the partition is in its position closest havebeen arrangedtooperate so that when the section is in its position pointing'towards thefelt roll the nozzle is open and air flows from it ina'directionparallel to the section towards the felt ro'll, while whenthe section'is in the position in which tion of the pocket. Thiscirculation, which is useless from the viewpoint of ventilation,constitutes a very remarkable fraction of the total flow into thepocket.

It has further been found by measurements that if in the space outsidethe pocket, opposite to the felt roll, an appropriately shaped partitionis placed, which extends close to the surface of the felt roll, the flowinto the pocket is not substantially changed from the situationprevailing in the absence of such a partition. The air flow has in facteven been noted to increase thanks to the partition. It is thenimportant, in order that the ventilation of the pocket might improve,that the air flow circulating around the felt roll cannot reenter thepocket, instead of which only fresh air from one side of the partitionfrom above the felt roll can flow into'the pocket. It is not possible,however, with the aid of the partition to influence the operation so asto achieve a uniform moisture profile of the web.

The object of the present invention is to accomplish for the drier adevice by the aid of which good ventilation of the pockets can beachieved and by means of which the moisture profile of the web can beinfluenced, utilizing the observations the gap between it and the feltroll is open the air flow is directed against the drying-cylinder.Between the sections in the margin of the partition pointing towards thefelt roll there may be partitions running in theweb direction, whichmainly serve the purposeof preventing flows in the direction across theweb in the space between the partition and drying cylinder from whichair flows towards the pocket. The said partition may consist of an aircurtain.

Since in a device according to the invention opposite to the felt rollbelonging to the pocket, outside the pocket, there' has been placed apartition transversal to the'felt and extending close to the surface ofthe felt roll, the edge of this partition pointing towards the felt rollhaving sections lying side by side and each of which is individuallyadjustableso that thegap between the section and the felt roll can bemade to have desired magnitude, it is possible to control the flow intothe pocket at the points desired so that the moisture profile of the webwill be uniform.

Theinvention is described in closer detail with reference to theembodiment examples presented in the attached drawings.

In the drawings,

FIG. l-presents schematicallypart of amulticylinder drier according tothe invention, in elevational view.

FIG. 2 shows an element belonging to the multicylinder drier accordingtoFIG. I, viewed from the direction indicated by the'line Il-ll in FIG. 1.

FIG. 3 presents a-multicylinder drier according to another embodiment ofthe invention, in elevational view.

FIG. 4 shows an element belonging to the multicylinder drier accordingto FIG. 3, viewed in the direction indicated by the line IV-IV in FIG.3. Y

FIG. 5 presents a multicylinder drier according to a third embodiment ofthe invention, in elevational view.

FIG. 6 shows an element belonging to the multicylinder drier accordingto FIG. 5, viewed in the direction indicated by the line VI-VI in FIG.5.

FIG. 7 presents a multicylinder drier according to a fourth embodimentof the invention, in elevational view.

FIG. 8 shows an element belonging to the machine accord-' ing to FIG. 7,viewed in the direction indicated by the line VIIIVIII in FIG. 7. i

To a multicylinder drier belong the drying cylinders in the upper row(in FIGS. 1, 3, and 7 of the drawing only two drying cylinders la and 1bshown) and the drying cylinders in the lower row, of which in thedrawing only one cylinder 1c has i been shown. In the spaces between thedrying cylinders in the upper row of the multicylinder drier there isalways one felt roll 2, and between the drying cylinders in the lowerrow, correspondingly also one felt roll. The drying felt 4 is carriedfrom the drying cylinder lb in the upper row over the felt roll 2 to thedrying cylinder lb in the same row. The drying felt travels from adrying cylinder in the lower row in analogous manner to another dryingcylinder. The web'which is being dried, 3, passes as even previouslyfrom the drying cylinder lb in the upper row to the drying cylinder 1cin the lower row and hence-further to the drying cylinder la in theupper row. For this reason in the multicylinder drier pockets 5 withopen ends are formed, as before. Arrows in the figures indicate thedirections of rotation of the drying cylinders la, lb and 1c and of thefelt roll 2.

In the multicylinder drier shown in FIG. 1 there has been placed outsidethe pocket and in the space 6 between two drying cylinders la and lb apartition 7 according to the invention transversely to the felt, themarginal portion of this partition which points towards the felt roll 2consisting of sections 7' located side by side in the direction acrossthe felt, which have been attached to the partition 7 by hinges 8 andeach of which in the direction of arrows A and B. As a consequence, no

whorl encircling the felt roll 2 can be formed. Opposite to a section insuch position the air in the pocket 5 is dry because v as a rule airarriving in the direction of arrows A and Bis dry' compared to the airescaping from the pocket in the direction of arrow C, return of thisair, at least its immediate return, into the pocket 5 being prevented asa result of the position of the section 7. If one of the sections is inthe up tumed position, which is illustrated by .the right half of FIG.1, a gap is formed between this section and the surface of the feltroll. As a result, a whorl is formed opposite to the section around the.felt roll 2, which is indicated by the arrows B, Dand C. In this caseonly part of the air entering the pocket 5 is dry air, .namely thatarriving in the direction of arrow A. Since furthermore, in thisposition, the section throttles the total flow of air into the pocket,the humidity of the air in the part of the pocket corresponding to thesection in question will be higher than the'humidity in'the partsgoverned by sections which have not been turned up. It is thus seen thatone may achieve in thepocket 5 alternating dryer and more humid zonesand thus exert an influence on the rate of drying with the aim ofattaining as uniform final drying of the web in the cross-machinedirection as possible.

The multicylinder drier presented in FIGS. 3 and 4 differs I from thatshown in FIGS. 1 and 2 only in that it comprises a nozzle arrangement,and corresponding parts have been denoted with the same referencenumerals in said figures. The

said nozzle arrangement merely serves the purpose of boosting the actionof the machine. The nozzle unit has been placed in the space between thepartition 7 and the drying cylinder lb, and it has been connected withan air header unit for supplying fresh air into the said space. In thesaid nozzle unit there is for'each section 7' on the margin of .thepartition 7 a corresponding nozzle 9 provided with a closing device, aflap, 10. The flap 10 of each nozzle 9 has been connected to cooperatewith its own section 7' so that their operation is as follows.

The closing device, the flap, l0'of each nozzle has been connected withthe respective section 7 by means of some devices known in themselves,not depicted in the drawing, so that the flapis in its opened positionwhen the section 7' is closest to the felt roll and prevents circulationaround the roll, in which instance fresh air flows in the direction ofarrows E at the point governed by the section in question into the spacebetween the partition 7 and the drying cylinder lb and thence into thepocket 5, as has been shown in the left part of FIG. 3, whereas the flap10 is closed when the section 7' is in a position such that a gap isformed between it and the felt roll, which'permits formation of a whorlencircling the felt roll; this situation is illustrated by the righthalf of FIG. 3. It is seen that in this manner drier and more'humid'zones can be produced in the pocket, with the result that uniformdrying of the web in the cross-machine direction-is achieved. v

In FIGS. 5 and 6a multicylinder drier has been presented which differsfrom the multicylinder drier shown in FIGS. 1

and 2 only in that the partition 7 hasbeen shaped to constitute a blowbox 11, into which air is supplied with the aid of blowers and of a pipesystem, and corresponding parts in said figures are indicated byidentical reference numerals. In said blow box 1 1 there is for eachsection 7' in the marginal part of the partition a corresponding nozzleslit, from which air is discharged into the space between the partition7 and the drying cylinder 1b, the direction of air flow depending on theposition in which the section 7' is. when the-section 7' is in aposition such that only a narrow gap remains between the section 7' andthe surface of the felt roll, that is in the position shown in the leftpart ofFIG. 5, then the air flow is directed as arrow F indicatestowards the felt roll and introduces fresh air into the space betweenthe partition 7 and the drying cylinder lb and also permits flow of airfrom the surroundings in the direction of arrows G into said space, inaddition to which it may perhaps even increase the said flow by itsinjector effect. If the section 7' in the marginal part of the partitionis in its upturned position, as in the right half 'of FIG. 5, wherebythere remains between the section 7' and the surface of the felt roll 2a gap which permits circulation around the felt roll 2, an air curtainis directed across the space between the partition 7 and the dryingcylinder lb, as the arrow F indicates. In this case the flow of air fromthe surroundings into said spaceis inhibited or at least impeded. It isthus seen that in the pocket 5 zones with various moisture contents canbe produced. By appropriate regulation of the sections, uniform dryingin the cross-machine direction of the web which is being dried isachieved. The multicylinder drier presented in FIGS. 7 and 8 differsfrom the multicylinder drier shown in FIGS. 1 and 2 7 only in that thesections 7 in the marginalstrip of the partition 7 are adjustable indifferent mannenand corresponding parts in said figures have beendenoted with identical reference numerals. The sections 7. have beenarranged to be displaceable in guides 7a on the partition 7 in thevertical direction of the partition. Each section 7 has been connectedin some manner known in itself with adjusting devices in order that thesections might be individually adjustable so that a gap of desiredmagnitude is achieved between the section and the surface of the feltroll. The action is similar to that of the machine presented in FIGS. 1and 2. This multicylinder drier, too, can be provided with devices suchas have been presented in FIGS. 3, 4 g

and 5, 6.

The invention is by no means confined merely to the embodimentspresented in the foregoing, and it can be varied in numerousdifferentways'within the scope of the'invention.

We claim:

1. Device for ventilating a pocket (5) of a multicylinder drier providedwith drying felts permeable to air, which pocket is defined by a felt(4) guided by a feltroll (2), by two freely travelling web portions (3)and by the surface of the drying cylinder (10) between them and is openat its ends, this device consisting of a partition (7) transversal tothe felt and placed opposite to the felt roll (2) belonging to thepocket (5 outside the pocket (5) between two drying cylinders (la, lb)

and one edge of which extends close to the surface of the felt roll (2),said partition (7) dividing the space between the drying cylinders intotwo parts from one of which an air flow induced by the running machineflows in the direction towards the pocket and into the other of whichair flows in the direction away from the pocket, characterized in thatthe marginal part of said partition (7) pointing towards the felt'rollconsists of sections (7) forming each others continuations in thedirection across the felt and each of which has been provided withindividual adjusting devices for such adjustment that between thesurface of the felt roll (2) and the edge of the section (7) a gap ofdesired width can be produced, through which air may flow in thedirection of rotation of the felt roll (2) from one side to the other ofthe partition.

2. Device according to claim 1, characterized inthat the sections (7)constituting the marginal part of the "partition pointing towards thefelt roll (2) are turnably attached to the partition 7).

3. Device according to claim 1, characterized in that the partition inits'entirety or at least its marginal part closest to the felt roll 2)consists of sections (7) transversal to the felt (4) which are movablein radial direction with reference to the surface of the felt roll (2),like shutters.

4. Device according to claim 1, characterized in that on the side of thepartition 7) from which flow into the pocket (5) takes place there hasbeen placed corresponding to each section (7') of the partition a nozzle(9) introducing fresh air and provided with a closing device (10), itsclosing device being arranged to operate so that when the free edge ofthe section (7) is in its position closest to the surface of the feltroll (2) the closing device (10) is open, while it is closed when thesection (7) is in the position in which the gap between the section (7)and the felt roll (2) is at its largest.

5. Device according to claim 2, characterized in that the partitionconsists of an air supply box under pressure and having a nozzle slit ateach turnable section (7') in the marginal part of the partition whichsupplies air flow into the space between the partition and the dryingcylinder from which flow into the pocket (5) takes place, and thesections (7) constituting the marginal part of the partition beingarranged to operate so that when a section (7') is in its positionpointing towards the felt roll (2) the nozzle is open and air flows fromit parallel to the section towards the felt roll (2), but when thesection (7) is in its upturned position, in which the gap between it andthe felt roll (2) is open, the air flow is directed against the dryingcylinder (lb).

6. Device according to claim 1, including means forming an air curtainbetween said partition and one of said drying cylinders.

1. Device for ventilating a pocket (5) of a multicylinder drier providedwith drying felts permeable to air, which pocket is defined by a felt(4) guided by a felt roll (2), by two freely travelling web portions (3)and by the surface of the drying cylinder (10) between them and is openat its ends, this device consisting of a partition (7) transversal tothe felt and placed opposite to the felt roll (2) belonging to thepocket (5), outside the pocket (5) between two drying cylinders (1a, 1b)and one edge of which extends close to the surface of the felt roll (2),said partition (7) dividing the space between the drying cylinders intotwo parts from one of which an air flow induced by the running machineflows in the direction towards the pocket and into the other of whichair flows in the direction away from the pocket, characterized in thatthe marginal part of said partition (7) pointing towards the felt rollconsists of sections (7'') forming each others'' continuations in thedirection across the felt and each of which has been provided withindividual adjusting devices for such adjustment that between thesurface of the felt roll (2) and the edge of the section (7'') a gap ofdesired width can be produced, through which air may flow in thedirection of rotation of the felt roll (2) from one side to the other ofthe partition.
 2. Device according to claim 1, characterized in that thesections (7'') constituting the marginal part of the partition pointingtowards the felt roll (2) are turnably attached to the partition (7). 3.Device according to claim 1, characterized in that the partition in itsentirety or at least its marginal part closest to thE felt roll (2)consists of sections (7'') transversal to the felt (4) which are movablein radial direction with reference to the surface of the felt roll (2),like shutters.
 4. Device according to claim 1, characterized in that onthe side of the partition (7) from which flow into the pocket (5) takesplace there has been placed corresponding to each section (7'') of thepartition a nozzle (9) introducing fresh air and provided with a closingdevice (10), its closing device being arranged to operate so that whenthe free edge of the section (7'') is in its position closest to thesurface of the felt roll (2) the closing device (10) is open, while itis closed when the section (7'') is in the position in which the gapbetween the section (7'') and the felt roll (2) is at its largest. 5.Device according to claim 2, characterized in that the partitionconsists of an air supply box under pressure and having a nozzle slit ateach turnable section (7'') in the marginal part of the partition whichsupplies air flow into the space between the partition and the dryingcylinder from which flow into the pocket (5) takes place, and thesections (7'') constituting the marginal part of the partition beingarranged to operate so that when a section (7'') is in its positionpointing towards the felt roll (2) the nozzle is open and air flows fromit parallel to the section towards the felt roll (2), but when thesection (7'') is in its upturned position, in which the gap between itand the felt roll (2) is open, the air flow is directed against thedrying cylinder (1b).
 6. Device according to claim 1, including meansforming an air curtain between said partition and one of said dryingcylinders.